116619

Appears in sequences

• Numbers k such that sigma(phi(k)) = sigma(k) where sigma is the sum of divisors function A000203 and phi is the Euler totient function A000010.at n=22A033631
• Numbers k such that 20*R_k + 7 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=9A056677
• Numbers k such that sigma(k*phi(k)) = sigma(k)^2.at n=8A082955
• Numbers k such that k and k^2 use only the digits 1, 3, 5, 6 and 9.at n=29A137035
• a(n) = ceiling(e^(n/3)).at n=34A214076